That doesnt sound healthy, you should reverse your reversed circadian rhythm. I dont buy that this is given to you and you cant change it. When i get up at 6 a couple of days in the row its hard at first but after a while it wake up at 6 without an alarm (provided i go to bet early enough). If i stay awake until 2 all the time, i wont get up before 9. Thats a habit and you can change it.
People who have sleep disorders such as Non-24 or DSPS will not set into a societally accepted cycle the way you do. While there are treatments for those conditions, they aren't as simple as just willing the problem to go away.
It is possible that the grandparent is simply habitually nocturnal... but it's equally possible that something else is happening.
That doesnt sound healthy, you should reverse your reversed circadian rhythm. I dont buy that this is given to you and you cant change it. When i get up at 6 a couple of days in the row its hard at first but after a while it wake up at 6 without an alarm (provided i go to bet early enough). If i stay awake until 2 all the time, i wont get up before 9. Thats a habit and you can change it.